A number of substituted .alpha.-alkyldihydrocinnamaldehydes are known odoriferous substances. W. Berends and L. M. v.d. Linde, Perfumery and Essential Oil Record, 58, 372 (1967). Some of these compounds, particulary p-isopropyl-.alpha.-methyldihydrocinnamaldehyde and p-t-butyl-.alpha.-methyldihydrocinnamaldehyde, are among the principal aromatic compounds used in the industry.
These compounds are usually made by the multistep process shown below which involves a condensation reaction of an aromatic aldehyde with the .alpha.-methylene of an aliphatic aldehyde ##STR1##
Other methods of synthesis are reviewed in the Berends article above. (R and R' are suitable substituents as defined herein.)
The success of this multistep process necessarily depends on the availability of the appropriate corresponding benzaldehyde and the ability to minimize side reactions such as self condensation of the aliphatic aldehyde and/or the Cannizzaro reaction.